The true value of film editing can only be appreciated when something is viewed without it. I was fortunate/unfortunate to have received a stark lesson in the values of editing today.
I was watching The Abyss, a cult-type favorite I really liked when it first came out and through the years, on television. Having not seen it in a while I was having a splendid time until I realized I was watching something that wasn't even in the film...and it was awful.
(Forgive me if you aren't familiar with the film.)
Ed Harris, rescued by the aliens at the bottom of the ocean after disarming the nuke activated by the crazy Seal guy, ends up in a long conversation with the aliens. They explain they are about to destroy civilization with a gigantic tsunami (hence the storm plot in the movie). They do this because humans have been so mean to each other; always warring and nuking and raping and nuking and killing and nuking...you get the picture. It was 1989 and Hollywood was in its ninth year of Republican leadership.
So, anyway, the aliens' bright idea is to teach us a lesson about destroying each other on a relatively small scale by taking us out on a large scale. They show Ed Harris a long series of news clips demonstrating how evil we are on a water TV complete with audio, by way of explanation. "You can't know" we will nuke the planet, pleads Ed Harris (in retrospect, a reasonable point).
But then, as if in all their television monitoring over the years they never once caught wind of a single kind act by a human being, they are touched by Ed Harris's selfless act of giving his own life to disarm the nuke. Because of it, they change their mind, even as gigantic, 1000-foot waves literally hover over most major cities and hundreds of thousands of terrified humans (most of which were American cities and people, just to remind the viewer where most of the evil comes from).
By the time Harris checks in with his underwater mates we have been treated to well over five minutes of preaching about our violent ways. Harris, in turn, gives us another few minutes as he relays the message to the crew and, ostensibly, the world. The highlight is when a guy on a surface vessel turns to the military officer on board and says something like "I guess you're going to have to find a new line of work." Because, after all, we received the alien wave message loud and clear. It's time to put away "childish things."
It was an absolutely putrid ten minutes of film, Hollywood holier-than-thou preaching 101, which I could have lived with taken on its own. But when you look at it over the whole of the movie, you realize it was the entire point of the film, personified by the slowly-going-insane Navy Seal character maniacally driven to nuke the unknown (the aliens).
Because of the unedited plot, Ed Harris goes from saving his crew (believable, ironically because humans have a long history of acts of kindness toward each other) to saving the world (the kind of stupid ideological tripe that gives people a Messiah complex).
It is an amazing sign of plot weakness, in my opinion, that an entire plot can be erased from a film simply by removing ten minutes from the climax. But worse, now that I know the original intention of the film makers, the entire movie - a pretty cool movie in its original form - is ruined.
Given that most people do not find it entertaining to be insulted, it was probably wise to remove the plot line from the original film. In other words, it was a wise editing decision and the movie was very successful. Far less wise was the release of the original ending, the sci-fi equivilent of the teary-eyed pollution Indian, which should never have seen the light of day.